Aluminum Intakes dont seal on X heads

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joes68340s

joes68340s

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I am forced to run a cast iron manifold that came on my 340. I am sure the block is decked. Pistons stick out about .020. Every manifold I have tried has not been able to seal at the bottom of the port. The top seems to be tight and the bottom has a gap. I not sure how I should measure to have the manifold cut to fit. the heads dont appear to be the problem. I have even checked the angle on my cast iron to the aluminum and they appear to be the same.
 
If the block and heads are decked/milled, you may heed to mill the intake as well to get it lower in the valley and sealuing correctly.
 
do the intake bolt holes line up with the threaded holes in the head or is some/more of the holes above or below the threaded holes?
 
BJR Racing said:
Sounds like the heads have been angle milled, and the intake side wasn't corrected.
Click to expand...

Well he said the deck was milled, which would have the same affect. So either pull the heads and mill them to the right angle, or do the intake (then that intake is useless to anyone else down the road if you want to sell)
 
I have tried with both the cork and without. But it dosent make much difference. The gap at the bottom of port is wider and doesnt seal.
 
GoodysGotaCuda said:
Well he said the deck was milled, which would have the same affect. So either pull the heads and mill them to the right angle, or do the intake (then that intake is useless to anyone else down the road if you want to sell)
Click to expand...

I can see that you've never done machine work, as there's a big difference between angle milling and flat milling and the correction on the intake side of the heads.

joes68340s
Measure the gap that you have at the bottom of the intake without the gaskets in place with a feeler gauage and when the heads come off you will have to have this much removed from the top side of the heads where the intake manifold butts up, and this will correct your problem and not destroy the manifolds. The intake should lay flat on the heads without the gaskets when finished, sounds like you'll have to take about .015-.020 off at a angle, so the bottom of the head where it meets the deck of the block will be 0 and the top will be the difference of the gap at the bottom, whatever the measurement is. So that the top will be cut and the bottom will just clean when finished.
 
If your aluminum intake has a gap at the bottom of the intake surface and a stock iron intake doesn't then I would say that your aluminum intake has an angle problem. If you heads were angle milled then you would have the same problem with any intake that you used.


Chuck
 
I have tried three different new manifolds and the would not seal at the bottom of the port. They pulled oil in an big vaccum leak. I have also had the heads off and I am not sure if I swapped them side to side or not. The cast manifold is the only manifold that will run without problems.
 
have you looked at your bolt hole alignment? I'm assuming you don't have alignment issues because the bolts go in all the manifolds you have tried. You never mentioned what you are using to seal the intakes without the gaskets. Edelbrock does not recommend the cork gaskets, in fact their installation instructions tell you to toss them and use a bead of rtv across the front and back. You have to make sure the bead is thick enough to seal and give it time to cure. I would take the bolts out and do a test fit like they mentioned in a previous post. Also when you say "port" are you talking about the gaps in the front and back? Where is the oil coming from to pull it in?
 
The problem is not with the new intakes. Your block and/or heads have been milled and any new intake you put on will need to be milled to match.


This is a very easy question to answer, no need to look for more.
 
I have to agree with fomulaS, If you milled the heads and block, you need to mill the intake. Now why the stocker fits and seals and the rest don't is beyond me. Maybe it was milled before. I did the same thing as far as milling the heads. I am running a set of j-heads that are milled quite a bit and there is no way in hell the intake would have sealed properly before milling it. My bolt holes wouldn't even line up. I thought about opening the holes but, I listened to everyone here and did what they said. Needless to say, my intake fits perfectly and sealed up first time it was installed. Has been running with no issues(at least the intake) for almost 6 months.
 
This engine was built by someone else long ago. The intake holes are close but a little tight. I cant run the cork end seals withe the aluminum manifolds but they work fine on the stock manifold.
 
Sounds to me like your motor may have been used in "stock eliminator" at one time being it sounds like the heads were angle milled and the stock intake was milled to match. If you have the new intakes milled to match the iron intake it will install just like the iron one does.

Chuck
 
But wouldn't it be better if the heads were corrected and then the intake could fit other engines and not be for one only?
 
BJR Racing said:
But wouldn't it be better if the heads were corrected and then the intake could fit other engines and not be for one only?
Click to expand...

If it were mine I would do this. Learned the hard way be careful after porting the 906 heads on my 451 I asked the machine shop I used in Az to dress the valve seats and cleanup the head gasket the charged me like 300 because the heads were as they said "all f'ed up and cut at some angle" so they had to remove the angle (with out asking they just added it to my bill), as I had cut the intake to match the heads I had to cut it again to rematch what a pain that was if I had done all my cuts on the heads it would have been a lot better. Again I have to say BJR is spot on here.
 
I dont think they were angle milled, but they were definately milled. I think they cut the intake sides and ends to make it fit. Like BJR sasid, they should have cut the intake flange of the head if possible so every intake fits...But... a mismatch of that level may be the result of a large cut. I wont mill more than .040 off the intake flanges, because you're cutting into the valve gasket sealing surface and I want that to remain thick as possible. So when milling heads or decks more than .040, I will mill the heads and intake, or just the intake so they all fit. The one paying me knows this. The one he sells the gine to years later may not. But, your machinist should be able to easliy fix that in any case.
 
BJR Racing said:
But wouldn't it be better if the heads were corrected and then the intake could fit other engines and not be for one only?
Click to expand...

I might be better to mill the head to match the stock intake angle but like Moper said you are going to lose material from the valve cover gasket surface. Plus you would have to remove the heads which would be more work. So it is hard to say which way would be best.


Chuck
 
Generally a intake will fit without machining up to .020-.025, so if you cut .030 you could have .055 off the deck surface and the manifold will still fit. If it's angle milled then it drops to less than .030 reguardless of the amount. I have cut heads for some .050 flat and then .050 angle milled and had a total of .030-.040 off the intake side and the manifold worked and fit just fine.

But I agree that at this point that it would be alot of work but to me is the only way to do it right.
 
Joe, I had the same problem with my motor. It was decked and the heads were milled. I sold the intake that was on it before I realized my new intake didnt fit. It did how ever fit fine with out the gaskets on the heads so I had the intake milled the thickness of the gaskets which was .060"
 
I agree with chuck, those heads were probably angle milled for a stock class. I believe this was done for a compression increase without showing during inspection/ I sold a set of heads to a guy a couple years ago who needed late 70's 360 head for this purpose. I don't know if you would have valve interference if you straighted the heads up. Don't waste the money have the intake milled by measuring with a feeler guage as the prior posts said and problem is solved, my.02 Walt ( but what do I know?):cheers:
 
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